Wednesday, November 12, 2014

"Finding Your Roots" Ep. 8 & The Autosomal DNA Tangle: Is AncestryDNA Right?

I really enjoyed episode 8 of "Finding Your Roots" focusing on British ancestry. I love to watch anything involving the British Empire. I mostly watch British TV programs when I watch TV. I've read more British novels than American. I have not found any proven English ancestry and would love to find some. I do have Scottish and Irish ancestry.

Sally Field's ancestry was the most fascinating. Some of her ancestors were loyalists, and one of her several times great-grandfather's was executed for treason during the American Revolution. His wife took the opportunity to relocate to Canada where she could receive free land for her family's loyalty. Sally Fields also has Mayflower ancestry that she was unaware of. One of her ancestors was a leader of the Plymouth Colony for many years, and presided over the first Thanksgiving. Sting's ancestors' lives revolved around the shipyards in England. He also had mariners in his family. The sea played such an important role in British history. Britain being an island meant they relied on sea trade to bring in commodities not available on the island. One of Stings ancestors was drowned, along with the rest of the crew, when their ship sank. Shipping was also important when it came to the lucrative Indian trade. Deepak Chopra's family benefited from the British colonization in some regards, but also suffered from some of the repercussions because of it. Deepak's father became a renowned Physician with the assistance of the British Governor of India. He was able to attend Medical school in Scotland which was a center for cutting edge medical training. When the British pulled out the unrest and relocations which resulted did negatively affect his family. As his Grandmother said the British came into India and reduced the native population to servitude  which caused the native population to lose the advanced knowledge they had previously attained. It would take generations to regain that knowledge.

Sally Field seemed to have traces of Native American ancestry in her DNA? Very likely to be true considering how long her ancestors have been in America

Rethinking the use of Autosomal DNA. I knew there were minor differences in segment size when looking at them in the company sites as compared with GEDmatch. I thought they were mostly slightly off, which is generally the case, but as I've now learned from a co-administrator of GEDmatch there can be significant differences (according to Family Tree DNA the differences are insignificant?). Entire segment deletions can occur. So this leads to the problem of who's numbers do you use when calculating relationships? If 10 cM segments and over are 99% IBD, and under that a significant number are IBS, then what if GEDmatch pronounces a segment to be over 10 cM's but Family Tree DNA has it significantly under 10 cM's? AncestryDNA has a point when they caution people about third party comparisons. The companies use complex calculations rather than just  cursory segment comparisons. They have better resources than the 3rd party citizen scientists' sites. I would still like to see a chromosome browser at AncestryDNA. If they had a chromosome browser at their own site they could oversee it, which would insure the segments are in line with their own findings, instead of risking misinterpretation at a 3rd party site.

AncestryDNA leans heavily on the often inaccurate trees, posted by testers, to suggest relationships. These tree connections can be wrong. Right now I'm dealing with a problem related to an AncestryDNA suggested relationship to a low confidence DNA match. This low confidence match is somewhat of a contradictory finding. A cousin of this Forgety match had taken the Y DNA test and did not match our Forgey testers. We assumed the close spelling of the name and proximity of the Forgetys and Forgeys on the map led to the mistaken idea they were related. This low confidence match of a Forgety to my Mom, who is a Forgey, is leading to speculation that there is a relationship after all. Since we cannot see how much DNA we share I'm not certain how valid this match is? Plus I noticed they have a Campbell line in Tennessee, and our Forgey line has a Campbell line said to have come from Tennessee.

So the problem making connections with the trees is few of us have trees going back 7 to 10 generations on every line. Sarah Campbell is actually only 4 generations from me, and 3 generations from my Mom. We don't know anything at all about her parents or ancestors. The only thing I have to go on is that Sarah Campbell/Wray lived in Indiana, while married, and died in 1847 at a young age. Her only child to live long enough to give an opinion on her place of birth was Polly T. Wray/Hall. She lived until 1920 and always claimed her mother was born in Tennessee. She was only 6 yrs. old when her Mom, Sarah, died. This leaves me with some uncertainty as to whether she would have any first hand source knowledge about where her mother was born?

We are in for a very interesting several weeks at AncestryDNA. No new matches will be posted until the reprocessing of over 500,000 tests is complete. In a couple of weeks from now we should be seeing the new results with the "false" matches eliminated. This could either turn out to be great or could be a complete disaster? We'll see. Read more here.

I'm getting ready to plunge into a Time magazine special publication called "How DNA Shapes Your Life". I just got it today.

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